Combine all the stock ingredients in a large saucepan and bring to the boil.
Meanwhile, mix the stock sauce ingredients together in a small bowl. When the stock comes to the boil, place the rice noodles in the stock, then one minute later, add the cauliflower and carrot.
After another minute, remove the pot from the heat and add the rest of the veg and the stock sauce. Mix well, taste and adjust the seasoning, if required, with extra splashes of ingredients from the stock sauce.
Divide the noodles and vegetables between four bowls. Ladle the soup into the bowls over the vegetables and noodles, and garnish with some sliced spring onions/scallions, coriander/cilantro leaves and toasted sesame seeds – plus some extra chilli/chili oil if you can handle the heat!